118 Pascals Triangle

Pascal’s Triangle

Given an integer numRows, return the first numRows of Pascal’s triangle.

In Pascal’s triangle, each number is the sum of the two numbers directly above it as shown:

 

Example 1:

**Input:** numRows = 5
**Output:** [[1],[1,1],[1,2,1],[1,3,3,1],[1,4,6,4,1]]

Example 2:

**Input:** numRows = 1
**Output:** [[1]]

 

Constraints:

1 <= numRows <= 30

impl Solution {
    pub fn generate(num_rows: i32) -> Vec<Vec<i32>> {
        let mut res : Vec<Vec<i32>> = Vec::new();
        let mut temp : Vec<i32> = Vec::new();
        temp.push(1);
        res.push(temp.clone());
        for i in 1..num_rows {
            let mut f = 0;
            let mut r = 1;
            let mut temp_to_add = Vec::new();
            temp_to_add.push(1);
            while (r < temp.len()) {
                temp_to_add.push(temp[f] + temp[r]);
                f += 1;
                r += 1;
            }
            temp_to_add.push(1);
            res.push(temp_to_add.clone());
            temp = temp_to_add;
        }
        res
    }
}